Apparently, the ruptured relationship between Theo Epstein and Larry Lucchino has become a major stumbling block in Epstein's desire to leave the Red Sox for the Cubs.

Our Comcast SportsNetNBC Sports colleague, David Kaplan of CSN Chicago, reported Saturday that "negotiations between the Cubs and the Boston Red Sox have turned increasingly contentious" over compensation for Epstein, and that the Cubs "have dug in their heels" against what the Sox are demanding in return for letting their general manager out of the final year of his Boston contract.

To further complicate matters, Kaplan's sources say Lucchino -- who, as president and CEO, is heading the Red Sox' side of the talks -- "is trying to make it very difficult for Epstein to accept his dream situation in Chicago because of his fractured relationship with his one-time protege".

"The Red Sox hold the cards here because they have their new GM in Ben Cherington and they control Theo for the next 12 months," a baseball executive told Kaplan. "If they want, they can force Theo to stay in Boston or on the sidelines for the next year. Can the Cubs go without a GM for the next 12 months? That would be an incredibly gutsy move but also a very risky one . . .

"Larry Lucchino is one of the most unreasonable people I have ever dealt with and, because of his frayed relationship with Theo Epstein, he is looking to make a point at the expense of Theo's happiness and his desire to go to Chicago. I didn't believe that ownership group for one second when they said that they wouldn't stand in Theo's way if he wanted out of Boston. They are furious that he wants out and they are trying to make a point."

According to earlier reports in various media outlets, the Cubs were looking to compensate the Red Sox with cash while the Sox were looking for prospects. In addition, the Red Sox are attempting to prevent Epstein from taking any of his Boston assistants to Chicago.